PEPTONES. 183 



membrane into another form, probably into an -albumin. 

 When anything interferes with this conversion, or when 

 they are otherwise introduced into the blood, they pass into 

 the urine. Diseases of the intestine, like carcinoma or 

 ulceration, may prevent conversion to albumin, giving rise 

 to enterogenic peptonuria. Peptone and albumose are 

 formed by the decomposition of albuminous substances by 

 other means than by digestion; as, for example, by putre- 

 faction. Diseases which are characterized by a formation 

 of peptones are often accompanied by peptonuria. This is 

 the so-called "pyogenic peptonuria/' It is found when 

 there is much formation of pus in a body-cavity, as in 

 croupous pneumonia and with deep-seated abscesses. 



The following tests can be used with urine containing 

 a considerable peptone : 



387. Heat 50 cubic centimeters of urine to boiling; 

 acidify if necessary with a few drops of acetic acid, filter- 

 ing if it precipitates, and, while hot, add powdered am- 

 monium sulphate to the filtrate as long as it dissolves and 

 until there are some crystals in the bottom. Filter after 

 cooling. This leaves the peptone in solution. To insure 

 complete precipitation of the other proteins the saturation 

 with ammonium sulphate may have to be repeated. When 

 this has been done and no further precipitate results, test 

 portions of the filtrate with (1) tannic acid with twice 

 its volume of water; (2) potassio-mercuric iodid. Each 

 should give a yellowish-white precipitate. The biuret 

 test can be tried, but is not as sensitive as the others. With 

 peptones, if no excess of copper sulphate is used, it should 

 give a pink with no shade of blue. A large amount of 

 sodium hydrate must be present. 



